US4404250A - Fire-retardant high pressure consolidated articles containing an air-laid web and method of producing same - Google Patents

Fire-retardant high pressure consolidated articles containing an air-laid web and method of producing same Download PDF

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Publication number
US4404250A
US4404250A US06/422,041 US42204182A US4404250A US 4404250 A US4404250 A US 4404250A US 42204182 A US42204182 A US 42204182A US 4404250 A US4404250 A US 4404250A
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Prior art keywords
resin
flame
retardant
air
fiber
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US06/422,041
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Theodore R. Clarke
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Formica Corp
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Formica Corp
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Classifications

    • DTEXTILES; PAPER
    • D21PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21HPULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H21/00Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
    • D21H21/14Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by function or properties in or on the paper
    • D21H21/34Ignifugeants
    • DTEXTILES; PAPER
    • D04BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04HMAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/40Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
    • D04H1/58Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by applying, incorporating or activating chemical or thermoplastic bonding agents, e.g. adhesives
    • D04H1/587Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by applying, incorporating or activating chemical or thermoplastic bonding agents, e.g. adhesives characterised by the bonding agents used
    • DTEXTILES; PAPER
    • D04BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04HMAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/40Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
    • D04H1/58Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by applying, incorporating or activating chemical or thermoplastic bonding agents, e.g. adhesives
    • D04H1/64Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by applying, incorporating or activating chemical or thermoplastic bonding agents, e.g. adhesives the bonding agent being applied in wet state, e.g. chemical agents in dispersions or solutions
    • DTEXTILES; PAPER
    • D06TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06MTREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
    • D06M11/00Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising
    • D06M11/80Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with boron or compounds thereof, e.g. borides
    • D06M11/82Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with boron or compounds thereof, e.g. borides with boron oxides; with boric, meta- or perboric acids or their salts, e.g. with borax
    • DTEXTILES; PAPER
    • D21PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21HPULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H27/00Special paper not otherwise provided for, e.g. made by multi-step processes
    • D21H27/18Paper- or board-based structures for surface covering
    • D21H27/22Structures being applied on the surface by special manufacturing processes, e.g. in presses
    • D21H27/26Structures being applied on the surface by special manufacturing processes, e.g. in presses characterised by the overlay sheet or the top layers of the structures
    • DTEXTILES; PAPER
    • D21PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21HPULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H17/00Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/20Macromolecular organic compounds
    • D21H17/33Synthetic macromolecular compounds
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10STECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S428/00Stock material or miscellaneous articles
    • Y10S428/92Fire or heat protection feature
    • Y10S428/921Fire or flameproofing
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00Stock material or miscellaneous articles
    • Y10T428/249921Web or sheet containing structurally defined element or component
    • Y10T428/249924Noninterengaged fiber-containing paper-free web or sheet which is not of specified porosity
    • Y10T428/249925Fiber-containing wood product [e.g., hardboard, lumber, or wood board, etc.]
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00Stock material or miscellaneous articles
    • Y10T428/31504Composite [nonstructural laminate]
    • Y10T428/31942Of aldehyde or ketone condensation product
    • Y10T428/31949Next to cellulosic
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00Stock material or miscellaneous articles
    • Y10T428/31504Composite [nonstructural laminate]
    • Y10T428/31942Of aldehyde or ketone condensation product
    • Y10T428/31949Next to cellulosic
    • Y10T428/31964Paper
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00Stock material or miscellaneous articles
    • Y10T428/31504Composite [nonstructural laminate]
    • Y10T428/31942Of aldehyde or ketone condensation product
    • Y10T428/31949Next to cellulosic
    • Y10T428/31964Paper
    • Y10T428/31967Phenoplast
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T442/00Fabric [woven, knitted, or nonwoven textile or cloth, etc.]
    • Y10T442/30Woven fabric [i.e., woven strand or strip material]
    • Y10T442/3927Including a paper or wood pulp layer
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T442/00Fabric [woven, knitted, or nonwoven textile or cloth, etc.]
    • Y10T442/60Nonwoven fabric [i.e., nonwoven strand or fiber material]
    • Y10T442/693Including a paper layer

Definitions

  • substrates comprising cellulosic fibers and a thermosetting resin composition useful, for example, in supporting decorative layers in the formation of high pressure decorative thermoset plastics laminates
  • said substrates comprise a plurality, i.e. about 2-10, of paper core sheets impregnated with a liquid thermosetting resin composition, said core sheets being prepared by impregnating a web of paper, prepared by a wet-laying process, with a solution or dispersion of a thermosetting resin composition in a volatile solvent, drying said impregnated web to reduce the volatile matter content to a desired level and cutting said impregnated, dried paper web into sheets of the required dimensions.
  • Sufficient core sheets are normally employed to provide laminates having thicknesses of about 0.25 mm-2.25 mm.
  • high pressure consolidated articles such as decorative laminates produced from a thermosetting resin containing fibrous cellulosic substrate, wherein the disadvantages of such articles made by conventional sheet processes are overcome or diminished, may be produced by using, as the substrate, an air-laid web comprising both cellulosic fibers and a thermosetting resin.
  • These high pressure articles exhibit a toughness superior to those produced conventionally which contain, as their core, a plurality of thermosetting resin impregnated Kraft paper sheets. This toughness is evidenced by the articles' increased resistance to stress-cracking. Additionally, these pressure articles also exhibit substantially equivalent uniform strength and dimensional properties regardless of the machine direction from which the measurement is taken.
  • air-laid fibrous webs are prepared by disintegrating fibrous, cellulosic material into its component fibers, transporting the fibers to a foraminous moving web-forming surface and depositing the fibers thereon to form a layer with the aid of suction applied to the under side of the surface.
  • fibrous, cellulosic material is disintegrated into its component fibers by a machine such as a hammermill or disc refiner and the fibers are transported to the forming surface in an air-stream.
  • Binder material is commonly applied to or admixed with the fibers as a particulate solid or as a liquid spray and the web deposited therefrom is then consolidated between nip rollers.
  • the binder When the binder is added as a solid to the air-fiber stream, it may be introduced into the hammermill or thereafter, but before deposition on the forming surface. Additionally, when the binder is used as a spray, the sprayed fibers may thereafter be dried and introduced as such into the forming apparatus.
  • a known apparatus for forming substrates by airlaying cellulosic fibers comprises: (i) an air-swept hammermill wherein cellulosic material is defibrated into its component fibers in an air-stream, (ii) ducting whereby the fiber containing air-stream is conveyed to a distributor, (iii) a distributor such as disclosed in U.S. Pat. No.
  • 3,518,706 comprising a housing having a perforated planar bottom wall and side walls, one or more impellers mounted to rotate about an axis substantially perpendicular to the bottom wall a short distance above and in non-contacting relationship with the upper surface of said bottom wall, inlet means for the fiber containing air-stream to enter the distributor, outlet means whereby fibrous material may be recycled to the hammermill and, optionally, a plate member located above said impellers and extending inwardly from the side walls of the housing so as to form a partition between a lower part and an upper part of said housing, said distributor being positioned so that the bottom wall is cooperatively located above the upper surface of (iv) a moving, foraminous belt upon the upper surface of which the cellulosic fibers are deposited to form a layer with the aid of (v) means for applying suction to the other surface of said belt and (vi) means for compacting the so-deposited cellulosic fiber layer, see U.S. Pat. No. 2,698,271.
  • the thermosetting resin When preparing a substrate adapted for use in the production of consolidated articles such as high pressure decorative laminates, the thermosetting resin must be randomly distributed throughout the deposited layer and there must be sufficient of the resin present to provide the desired properties to the heat and pressure consolidated laminate.
  • the resin content of the substrate lies in the range from about 20% to about 35%, by weight preferably from about 25% to about 30%, based on the total weight of the substrate.
  • an air-laid substrate having uniformity of composition and basis weight and comprising fibers and thermosetting resin, such as by means of an apparatus of the type described above, it is preferable to operate under conditions such that the air has a relative humidity within the range of about 40% to 80%, preferably about 50% to 70%.
  • the air employed has a humidity level outside of the disclosed range, then deposition problems may arise in that at too high a humidity clogging of the ducting and screen may occur while at too low a humidity problems may arise due to static electrical charges on the fibers.
  • boric acid or ammonium pentaborate in particulate form, i.e., particle sizes ranging from about 0.1 micron to 200 microns, may be added along with the fibers, and resin, if the resin is used as a solid.
  • the boric acid and ammonium pentaborate are used in flame-retarding amounts, with the amount of boric acid used generally ranging from about 5.0 to about 25.0 percent, by weight, based on the weight of the fiber, resin and flame-retardant in the core, the amount of ammonium pentaborate generally used ranging from about 4.0 to about 25.0 percent, same basis.
  • a preferred range of either flame-retardant comprises from about 5.0-12.0 percent, same basis.
  • Boric acid and ammonium pentaborate are known flame-retardants which are normally used in conjunction with other additives such as borates, phosphates etc. They are only slightly soluble in water and therefore cannot be used to impart flame-retarding properties to paper sheets produced by the conventional wet-process and are not very soluble in phenolic resins. They, therefore, cannot be applied to wet-laid paper sheets during their impregnation with resin.
  • the boric acid or ammonium pentaborate can be added along with the fibers or resin or both, or may be added individually, during the formation of the air-laid web so long as they are uniformly distributed throughout the length and breadth of the web during its formation.
  • a monostichous substrate comprising a thermosetting resin, flame-retardant and cellulosic fibers which substrate is uniform in composition and basis weight and is of a thickness such that a single ply is useful in the production of such products as heat and pressure consolidated articles.
  • thermosetting resin containing monostichous substrate of randomly oriented, substantially non-hydrogen bonded cellulosic fibers is formed using an apparatus of the type described above, by:
  • the fibrous, cellulosic material employed may comprise any material such as chemical, semi-chemical or mechanical paper pulp, cardboard, linerboard, corrugated box fiber and waste paper and the like, provided that after defibration in the hammermill it comprises fibers of an average length of 0.5 mm to 2.5 mm. Although fibers produced from wood are preferred, fibers produced from straw, grass, bagasse, cotton or synthetics, may be used or in admixture. If the cellulosic material feed is in bulk form, then it is preferred to use a bale-breaker or similar equipment to partially disintegrate the material before it is fed to the hammermill.
  • the air fed to the hammermill may be humidified to the above-specified extent either internally or externally of the substrate forming apparatus.
  • the apparatus may be sited in a room, the air in which is humidified to the required degree and drawn through the apparatus at the required rate.
  • the air may be drawn into the apparatus and there humidified such as by steam or water spray means to the required level. It is preferred to humidify the air internally of the apparatus as such allows for quicker adjustment of the humidity than is possible with external humidification and further allows the room air to be controlled independently so as to provide more amenable working conditions.
  • the said thermosetting resin may comprise any thermosetting resin which provides the required properties in the substrate prepared therefrom.
  • the resin may comprise, for example, a one-step or two-step phenol-formaldehyde resin, a melamine-formaldehyde resin, etc. and said resins may contain known extenders, if desried. It is preferred to employ a particulate, thermosetting resin and even more preferred to employ a thermosetting phenol-formaldehyde resin.
  • Such a particulate resin may be prepared by forming a solid, thermosetting resin in bulk or lump form and then grinding or crushing to provide the desired particle size or, more preferably, it may be prepared in particulate form by known emulsion condensation techniques.
  • the mean particle size of the thermosetting resin should range from about 20 microns to about 200 microns, preferably from about 50 to 150 microns.
  • thermosettting resin as well as the flame-retardant powder, may be incorporated into the air-fiber stream by any suitable means and at any suitable position prior to deposition.
  • the resin and/or flame-retardant may be introduced into the hammermill, into the ducting between the hammermill and the distributor, or into the distributor.
  • Suitable introductory means are known and include spraying means, gate-valves, vibratory-and-screw-feeders etc. It is preferred to employ screw feeders which employ a positive feed principle and can be controlled more precisely to give the feed rate of resin and/or flame-retardant desired.
  • the air-laid layer may be pre-consolidated between platens or nip rollers as may be most convenient and the preconsolidating means may be heated or cooled, if desired. If said means are heated, then the pre-consolidation must be such that while there may be some conversion of a minor amount of the thermosetting resin to the thermost form, a substantial proportion of the resin is still in the thermosetting form after the pre-consolidation operation.
  • the airlaid layer, before pre-consolidation must be of such a thickness that after heat and pressure consolidation the resultant article will range in thickness from about 0.25 mm to about 2.25 mm. Air-laid webs are thus deposited on the belt, which may be constructed of metal or other material such as plastic, cloth etc.
  • thermoset decorative laminate comprising, in superimposed relationship:
  • thermost resin containing, monostichous substrate of air-laid, randomly oriented, substantially non-hydrogen bonded cellulosic fibers having an average length of 0.5 mm to 2.5 mm, said substrate being from about 0.25 mm to about 2.25 mm thick and containing from about 20% to about 35%, by weight, of resin, based on the total weight of fiber and resin in I and a flame-retarding amount of boric acid or ammonium pentaborate,
  • thermoset resin impregnated decorative sheet (II) a thermoset resin impregnated decorative sheet and optionally,
  • thermoset resin impregnated alpha-cellulose overlay sheet (III) a thermoset resin impregnated alpha-cellulose overlay sheet.
  • thermoset, high pressure, decorative laminates comprises:
  • thermosetting resin impregnated decorative sheet (B) a thermosetting resin impregnated decorative sheet and, optionally,
  • thermosetting resin impregnated alpha-cellulose overlay sheet (C) a thermosetting resin impregnated alpha-cellulose overlay sheet
  • thermosetting resin impregnated decor sheet employed in the present invention may comprise any of those decor sheets known to provide the decorative surface to a decorative laminate and includes decorative woven or non-woven fabrics, colored or printed paper sheets, wood veneer, cork, and the like.
  • the resin may be of any of those known for use in the production of thermoset laminates but it is preferred to use those ⁇ noble ⁇ thermosetting resins known for such use and it is most preferred to employ a high quality printed or colored decorative paper sheet impregnated with a thermosetting melamine-formaldehyde resin composition.
  • ⁇ noble ⁇ thermosetting resins is meant those resins which show no appreciable darkening or color change on conversion from the thermosetting to the thermoset state.
  • thermosetting melamine-formaldehyde resin When a decorative woven or non-woven fabric sheet or a printed paper sheet is employed, it is preferred to use, in addition thereto, a surfacing overlay sheet known for use in the production of conventional thermoset laminates. More especially, it is preferred to use a light weight, high-quality, unfilled alpha-cellulose paper sheet impregnated with the same kind of thermosetting resin composition as used to impregnate the decorative sheet and, still more preferably, an overlay sheet impregnated with a thermosetting melamine-formaldehyde resin may be employed.
  • the optional overlay sheet may comprise any of those overlay sheets known to provide a protective, abrasion-resistant surface to decorative laminates.
  • these overlay sheets comprise alpha-cellulose paper which is impregnated with a noble thermosetting resin, preferably melamine/formaldehyde, and which become transparent upon heat and pressure consolidation of the laminate assembly.
  • the heat and pressure consolidation conducted to produce the unitary article or decorative laminate is suitably carried out using that machinery, equipment, pressplates, temperature, pressure and press-time used for preparing decorative thermoset laminates from the conventional impregnated kraft paper core layers. Pressures ranging from about 700 to about 1400 psi and temperatures ranging from about 120° to 150° C., are commonly employed.
  • the pre-consolidated layer is further consolidated by heat and pressure so that in the resultant article the thickness of the air-laid substrate is reduced by a factor of about two to about ten. More especially, the heat and pressure consolidation is effected so that in the final article, the substrate has a thickness of from about 0.25 mm to about 2.25 mm, as mentioned above.
  • thermosetting resin impregnated decor sheet and, optionally, a thermosetting resin impregnated alpha-cellulose overlay sheet the invention is not so limited and also encompasses laminates comprising a substrate produced from more than one monostichous, non-hydrogen bonded, air-laid webs of different thickness, fiber size, fiber type etc., the noble thermosetting resin impregnated decor sheet and, optionally, the noble thermosetting resin impregnated overlay sheet, with the thickness of the multi-layered web falling within the ranges expressed above.
  • Defibrated kraft fibers are mixed with powdered phenol/formaldehyde resin and boric acid powder and formed onto a stationary screen with the aid of suction applied to the underside of said screen.
  • the deposited fiber-resin-boric acid layer is preconsolidated, at a pressure of 2300 psi, to a thickness of about 2.25 mm and contains the specified amount of boric acid.
  • thermoset resinous laminate assembly comprising:
  • thermosetting melamine/formaldehyde resin to a resin content of about 40%
  • the assembly After positioning between separating sheets, the assembly is heat and pressure consolidated at 1400 psi and 145° C. to a unitary thermoset decorative laminate with a thickness of about 1.12 mm.
  • the resultant laminate is then subjected to a series of tests to determine its flame-retardant properties.
  • the results are set forth in Table I, below, in addition to results using other known flame-retardant additives and fibers.
  • the flame-retardant should result in a Limiting Oxygen Index (ASTM-D-2863-70) of at least about 42, an Arapahoe Smoke (Arapahoe Chemicals) of less than about 1.7, an ASTM E-84 Smoke of 10 or less and Flame Spread of 20 or less.
  • ASTM-D-2863-70 Limiting Oxygen Index
  • ASTM E-84 Smoke Arapahoe Chemicals
  • Flame Spread 20 or less.
  • the Swedish Fire Box (Nordtest Fire 004) results should be Class I.
  • Example 1 The procedure of Example 1 is again followed except that the overlay and decor paper are eliminated.
  • (15) boric acid is used at 12% the Oxygen Index is 53, the Arapahoe Smoke is 1.3 and the ASTM E-84 Smoke & Flame Spread are 0/0 and 15/15, respectively.
  • Example 16C when considered with Example 10C above shows the inconsistency of DOT as a flame-retardant herein. See also Table V, below.
  • Plate Scumming refers to the damage done to the press plate during heat and pressure consolidation due to an interaction between the resin and the flame-retardant additive.

Abstract

The invention relates to flame-retardant, high pressure consolidated articles containing an air-laid web and to a method of preparing such articles wherein boric acid or ammonium pentaborate is added as a flame-retardant additive.

Description

BACKGROUND OF THE INVENTION
The production of substrates comprising cellulosic fibers and a thermosetting resin composition useful, for example, in supporting decorative layers in the formation of high pressure decorative thermoset plastics laminates is well known. Conventionally, said substrates comprise a plurality, i.e. about 2-10, of paper core sheets impregnated with a liquid thermosetting resin composition, said core sheets being prepared by impregnating a web of paper, prepared by a wet-laying process, with a solution or dispersion of a thermosetting resin composition in a volatile solvent, drying said impregnated web to reduce the volatile matter content to a desired level and cutting said impregnated, dried paper web into sheets of the required dimensions. Sufficient core sheets are normally employed to provide laminates having thicknesses of about 0.25 mm-2.25 mm.
Recently, it has been found that high pressure consolidated articles such as decorative laminates produced from a thermosetting resin containing fibrous cellulosic substrate, wherein the disadvantages of such articles made by conventional sheet processes are overcome or diminished, may be produced by using, as the substrate, an air-laid web comprising both cellulosic fibers and a thermosetting resin. These high pressure articles exhibit a toughness superior to those produced conventionally which contain, as their core, a plurality of thermosetting resin impregnated Kraft paper sheets. This toughness is evidenced by the articles' increased resistance to stress-cracking. Additionally, these pressure articles also exhibit substantially equivalent uniform strength and dimensional properties regardless of the machine direction from which the measurement is taken.
One of the most difficult to solve problems the consolidated article industry has been faced with in recent years is to improve the flame-retardancy of the articles so that they can be used in particular service applications wherein non-flammability is critical such as on ships and naval vessels.
When producing such articles from core materials composed of a plurality of resin impregnated paper sheets, the addition of flame-retardant additives must be accomplished either during the production of the paper sheets per se or during the impregnation of the sheets with resin. To retain the flame-retardant additive in the paper during the paper-making process is extremely difficult and to add the additive during paper sheet impregnation with the resin requires that either the resin be a solvent for the flame-retardant or that the resin bath be continuously agitated to retain the flame-retardant in suspension in the resin bath while the paper is passing therethrough.
SUMMARY OF THE INVENTION
Using air-laid webs as core materials, the incorporation of flame-retardant additives therein so as to provide heat and pressure consolidated articles having sufficient flame-retardancy to pass stringent regulations, has now been accomplished. By the use of particles of boric acid or ammonium pentaborate it has been found that excellent flame-retardant heat and pressure consolidated articles can be produced having low smoke levels without interfering with the basic process steps of the production of the article and without causing scumming of the laminate press plates.
BACKGROUND OF THE INVENTION
The manufacture of air-laid fibrous webs is well-known, and fibrous cellulosic webs useful for producing many diverse products have been manufactured commercially.
Commonly, air-laid fibrous webs are prepared by disintegrating fibrous, cellulosic material into its component fibers, transporting the fibers to a foraminous moving web-forming surface and depositing the fibers thereon to form a layer with the aid of suction applied to the under side of the surface. Usually the fibrous, cellulosic material is disintegrated into its component fibers by a machine such as a hammermill or disc refiner and the fibers are transported to the forming surface in an air-stream. Binder material is commonly applied to or admixed with the fibers as a particulate solid or as a liquid spray and the web deposited therefrom is then consolidated between nip rollers. When the binder is added as a solid to the air-fiber stream, it may be introduced into the hammermill or thereafter, but before deposition on the forming surface. Additionally, when the binder is used as a spray, the sprayed fibers may thereafter be dried and introduced as such into the forming apparatus.
A known apparatus for forming substrates by airlaying cellulosic fibers comprises: (i) an air-swept hammermill wherein cellulosic material is defibrated into its component fibers in an air-stream, (ii) ducting whereby the fiber containing air-stream is conveyed to a distributor, (iii) a distributor such as disclosed in U.S. Pat. No. 3,518,706, comprising a housing having a perforated planar bottom wall and side walls, one or more impellers mounted to rotate about an axis substantially perpendicular to the bottom wall a short distance above and in non-contacting relationship with the upper surface of said bottom wall, inlet means for the fiber containing air-stream to enter the distributor, outlet means whereby fibrous material may be recycled to the hammermill and, optionally, a plate member located above said impellers and extending inwardly from the side walls of the housing so as to form a partition between a lower part and an upper part of said housing, said distributor being positioned so that the bottom wall is cooperatively located above the upper surface of (iv) a moving, foraminous belt upon the upper surface of which the cellulosic fibers are deposited to form a layer with the aid of (v) means for applying suction to the other surface of said belt and (vi) means for compacting the so-deposited cellulosic fiber layer, see U.S. Pat. No. 2,698,271.
DESCRIPTION OF THE INVENTION INCLUDING PREFERRED EMBODIMENTS
When preparing a substrate adapted for use in the production of consolidated articles such as high pressure decorative laminates, the thermosetting resin must be randomly distributed throughout the deposited layer and there must be sufficient of the resin present to provide the desired properties to the heat and pressure consolidated laminate. In the production of the high pressure decorative laminates, the resin content of the substrate lies in the range from about 20% to about 35%, by weight preferably from about 25% to about 30%, based on the total weight of the substrate.
In the formation of an air-laid substrate having uniformity of composition and basis weight and comprising fibers and thermosetting resin, such as by means of an apparatus of the type described above, it is preferable to operate under conditions such that the air has a relative humidity within the range of about 40% to 80%, preferably about 50% to 70%.
If the air employed has a humidity level outside of the disclosed range, then deposition problems may arise in that at too high a humidity clogging of the ducting and screen may occur while at too low a humidity problems may arise due to static electrical charges on the fibers.
In order to impart flame-retardency to the air-laid substrates so that they may be used, when heat and pressure consolidated, as such or as components in, for example, decorative laminates, it has now been found that boric acid or ammonium pentaborate, in particulate form, i.e., particle sizes ranging from about 0.1 micron to 200 microns, may be added along with the fibers, and resin, if the resin is used as a solid. The boric acid and ammonium pentaborate are used in flame-retarding amounts, with the amount of boric acid used generally ranging from about 5.0 to about 25.0 percent, by weight, based on the weight of the fiber, resin and flame-retardant in the core, the amount of ammonium pentaborate generally used ranging from about 4.0 to about 25.0 percent, same basis. A preferred range of either flame-retardant comprises from about 5.0-12.0 percent, same basis.
Boric acid and ammonium pentaborate are known flame-retardants which are normally used in conjunction with other additives such as borates, phosphates etc. They are only slightly soluble in water and therefore cannot be used to impart flame-retarding properties to paper sheets produced by the conventional wet-process and are not very soluble in phenolic resins. They, therefore, cannot be applied to wet-laid paper sheets during their impregnation with resin.
The boric acid or ammonium pentaborate can be added along with the fibers or resin or both, or may be added individually, during the formation of the air-laid web so long as they are uniformly distributed throughout the length and breadth of the web during its formation.
By the method of this invention, there is provided a monostichous substrate comprising a thermosetting resin, flame-retardant and cellulosic fibers which substrate is uniform in composition and basis weight and is of a thickness such that a single ply is useful in the production of such products as heat and pressure consolidated articles.
The thermosetting resin containing monostichous substrate of randomly oriented, substantially non-hydrogen bonded cellulosic fibers is formed using an apparatus of the type described above, by:
(a) feeding fibrous, cellulosic material to an air-swept hammermill and defibrating the material therein to provide cellulosic fibers of an average length of about 0.5 mm to 2.5 mm, preferably about 0.75 mm to 2.0 mm in the presence of humidified air, the relative humidity of which preferably ranges from about 40% to about 80% to thereby form an air-fiber stream;
(b) incorporating into said air-fiber stream from about 20% to about 35%, by weight, of a thermosetting resin, said weight being based on the total weight of resin, in flame-retardant and fiber, and a flame-retarding amount of boric acid or ammonium pentaborate to thereby form an air-fiber-resin flame retardant stream;
(c) passing said air-fiber-resin flame retardant stream to a distributor;
(d) agitating said stream within the distributor by impeller means;
(e) causing said stream to pass through the perforated bottom wall of the distributor;
(f) depositing the fibers, boric acid or ammonium pentaborate and resin onto a moving foraminous belt to form a layer having a thickness of from about 5 mm to about 100 mm, preferably about 10 mm to 80 mm by the operation of the suction means,
(g) pre-consolidating the deposited layer to a thickness of from about 0.5 mm to about 10 mm, preferably about 1.0 to about 8.0 mm to form a pre-consoliated layer and
(h) heat and pressure consolidating said preconsolidated layer.
The fibrous, cellulosic material employed may comprise any material such as chemical, semi-chemical or mechanical paper pulp, cardboard, linerboard, corrugated box fiber and waste paper and the like, provided that after defibration in the hammermill it comprises fibers of an average length of 0.5 mm to 2.5 mm. Although fibers produced from wood are preferred, fibers produced from straw, grass, bagasse, cotton or synthetics, may be used or in admixture. If the cellulosic material feed is in bulk form, then it is preferred to use a bale-breaker or similar equipment to partially disintegrate the material before it is fed to the hammermill.
The air fed to the hammermill may be humidified to the above-specified extent either internally or externally of the substrate forming apparatus. Thus the apparatus may be sited in a room, the air in which is humidified to the required degree and drawn through the apparatus at the required rate. Alternatively, the air may be drawn into the apparatus and there humidified such as by steam or water spray means to the required level. It is preferred to humidify the air internally of the apparatus as such allows for quicker adjustment of the humidity than is possible with external humidification and further allows the room air to be controlled independently so as to provide more amenable working conditions.
The said thermosetting resin may comprise any thermosetting resin which provides the required properties in the substrate prepared therefrom. The resin may comprise, for example, a one-step or two-step phenol-formaldehyde resin, a melamine-formaldehyde resin, etc. and said resins may contain known extenders, if desried. It is preferred to employ a particulate, thermosetting resin and even more preferred to employ a thermosetting phenol-formaldehyde resin. Such a particulate resin may be prepared by forming a solid, thermosetting resin in bulk or lump form and then grinding or crushing to provide the desired particle size or, more preferably, it may be prepared in particulate form by known emulsion condensation techniques. The mean particle size of the thermosetting resin should range from about 20 microns to about 200 microns, preferably from about 50 to 150 microns.
The thermosettting resin, as well as the flame-retardant powder, may be incorporated into the air-fiber stream by any suitable means and at any suitable position prior to deposition. Thus, the resin and/or flame-retardant may be introduced into the hammermill, into the ducting between the hammermill and the distributor, or into the distributor. Suitable introductory means are known and include spraying means, gate-valves, vibratory-and-screw-feeders etc. It is preferred to employ screw feeders which employ a positive feed principle and can be controlled more precisely to give the feed rate of resin and/or flame-retardant desired.
The air-laid layer may be pre-consolidated between platens or nip rollers as may be most convenient and the preconsolidating means may be heated or cooled, if desired. If said means are heated, then the pre-consolidation must be such that while there may be some conversion of a minor amount of the thermosetting resin to the thermost form, a substantial proportion of the resin is still in the thermosetting form after the pre-consolidation operation. The airlaid layer, before pre-consolidation, must be of such a thickness that after heat and pressure consolidation the resultant article will range in thickness from about 0.25 mm to about 2.25 mm. Air-laid webs are thus deposited on the belt, which may be constructed of metal or other material such as plastic, cloth etc.
According to the instant invention, there is also provided a flame-retardant heat and pressure consolidated, high pressure, thermoset decorative laminate comprising, in superimposed relationship:
(I) a thermost resin containing, monostichous substrate of air-laid, randomly oriented, substantially non-hydrogen bonded cellulosic fibers having an average length of 0.5 mm to 2.5 mm, said substrate being from about 0.25 mm to about 2.25 mm thick and containing from about 20% to about 35%, by weight, of resin, based on the total weight of fiber and resin in I and a flame-retarding amount of boric acid or ammonium pentaborate,
(II) a thermoset resin impregnated decorative sheet and optionally,
(III) a thermoset resin impregnated alpha-cellulose overlay sheet.
In accordance with the instant invention, the method for preparing said thermoset, high pressure, decorative laminates comprises:
(1) forming a laminate assembly comprising, in superimposed relationship:
(A) a monostichous, air-laid substrate of randomly oriented fibers of 0.5-2.5 mm average length, containing from about 20% to about 35%, same basis as above, of a thermosetting resin and a flame-retarding amount of boric acid or ammonium pentaborate and of sufficient thickness to provide, when heat and pressure consolidated, a final thickness of from about 0.25 mm to about 2.25 mm to the resultant laminate,
(B) a thermosetting resin impregnated decorative sheet and, optionally,
(C) a thermosetting resin impregnated alpha-cellulose overlay sheet; and
(2) consolidating said assembly to a unitary thermoset laminate structure by the application of heat and pressure thereto.
The thermosetting resin impregnated decor sheet employed in the present invention may comprise any of those decor sheets known to provide the decorative surface to a decorative laminate and includes decorative woven or non-woven fabrics, colored or printed paper sheets, wood veneer, cork, and the like. The resin may be of any of those known for use in the production of thermoset laminates but it is preferred to use those `noble` thermosetting resins known for such use and it is most preferred to employ a high quality printed or colored decorative paper sheet impregnated with a thermosetting melamine-formaldehyde resin composition. By `noble` thermosetting resins is meant those resins which show no appreciable darkening or color change on conversion from the thermosetting to the thermoset state.
When a decorative woven or non-woven fabric sheet or a printed paper sheet is employed, it is preferred to use, in addition thereto, a surfacing overlay sheet known for use in the production of conventional thermoset laminates. More especially, it is preferred to use a light weight, high-quality, unfilled alpha-cellulose paper sheet impregnated with the same kind of thermosetting resin composition as used to impregnate the decorative sheet and, still more preferably, an overlay sheet impregnated with a thermosetting melamine-formaldehyde resin may be employed.
The optional overlay sheet may comprise any of those overlay sheets known to provide a protective, abrasion-resistant surface to decorative laminates. Preferably, these overlay sheets comprise alpha-cellulose paper which is impregnated with a noble thermosetting resin, preferably melamine/formaldehyde, and which become transparent upon heat and pressure consolidation of the laminate assembly.
The heat and pressure consolidation conducted to produce the unitary article or decorative laminate is suitably carried out using that machinery, equipment, pressplates, temperature, pressure and press-time used for preparing decorative thermoset laminates from the conventional impregnated kraft paper core layers. Pressures ranging from about 700 to about 1400 psi and temperatures ranging from about 120° to 150° C., are commonly employed.
The pre-consolidated layer is further consolidated by heat and pressure so that in the resultant article the thickness of the air-laid substrate is reduced by a factor of about two to about ten. More especially, the heat and pressure consolidation is effected so that in the final article, the substrate has a thickness of from about 0.25 mm to about 2.25 mm, as mentioned above.
Further, while it is preferred to prepare laminates comprising a single substrate made in accordance with the invention, a single thermosetting resin impregnated decor sheet and, optionally, a thermosetting resin impregnated alpha-cellulose overlay sheet, the invention is not so limited and also encompasses laminates comprising a substrate produced from more than one monostichous, non-hydrogen bonded, air-laid webs of different thickness, fiber size, fiber type etc., the noble thermosetting resin impregnated decor sheet and, optionally, the noble thermosetting resin impregnated overlay sheet, with the thickness of the multi-layered web falling within the ranges expressed above.
The following examples are set forth for purposes of illustration only and are not to be construed as limitations on the present invention except as set forth in the appended claims. All parts and percentages are by weight unless otherwise specified.
EXAMPLES 1-14
Defibrated kraft fibers are mixed with powdered phenol/formaldehyde resin and boric acid powder and formed onto a stationary screen with the aid of suction applied to the underside of said screen. The deposited fiber-resin-boric acid layer is preconsolidated, at a pressure of 2300 psi, to a thickness of about 2.25 mm and contains the specified amount of boric acid.
After conditioning the compacted, monostichous, fiber-resin-boric acid core layer at 60% relative humidity for 24 hours, a decorative thermoset resinous laminate assembly is formed comprising:
(a) the above monostichous core layer,
(b) a printed decor paper impregnated with a thermosetting melamine/formaldehyde resin to a resin content of about 40% and,
(c) an alpha-cellulose overlay sheet impregnated with a thermosetting melamine/formaldehyde resin to a resin content of about 60%.
After positioning between separating sheets, the assembly is heat and pressure consolidated at 1400 psi and 145° C. to a unitary thermoset decorative laminate with a thickness of about 1.12 mm. The resultant laminate is then subjected to a series of tests to determine its flame-retardant properties. The results are set forth in Table I, below, in addition to results using other known flame-retardant additives and fibers.
To be considered effective, the flame-retardant should result in a Limiting Oxygen Index (ASTM-D-2863-70) of at least about 42, an Arapahoe Smoke (Arapahoe Chemicals) of less than about 1.7, an ASTM E-84 Smoke of 10 or less and Flame Spread of 20 or less. The Swedish Fire Box (Nordtest Fire 004) results should be Class I.
                                  TABLE I                                 
__________________________________________________________________________
                                             Swedish                      
                            Arapahoe                                      
                                  ASTM E = 84*                            
                                             Fire                         
Example                                                                   
     Fiber Flame-Retardant %                                              
                     Oxygen Index                                         
                            Smoke Test                                    
                                  Smoke                                   
                                      Flame Spread                        
                                             Box                          
__________________________________________________________________________
 1   Linerboard                                                           
           Boric Acid                                                     
                 12  53      1.35 5/0 15/15  Class I                      
 2   Corrugated                                                           
           "     8   60     --    --  --     Class I                      
 3   "     "     7   51     --    --  --     Class I                      
 4C  "     "     4   45     --    --  --     Class II                     
 5C  "     APP   10  55     --    --  --     Class I                      
 6C  "     "     8   49     --    --  --     Class I                      
 7C  Linerboard                                                           
           "     10  51     3.0   30/35                                   
                                      15/20  Class I                      
 8C  "     "     8   44     3.0   35/35                                   
                                      20/20  Class I                      
 9C  "     "     6   43     3.0   40/30                                   
                                      20/20  Class II                     
10C  "     DOT   15  43     1.1   30/0                                    
                                      15/20  Class I                      
11C  "     "     10  39     1.1   15/20                                   
                                      20/15  Class II                     
12C  "     "     9   39     1.4   15/20                                   
                                      20/15  Class II                     
13C  "     "     5   37     1.2   --  --     Class II                     
14C  "     "     10  39     0.9   --  --     Class II                     
__________________________________________________________________________
 *2 Test Samples                                                          
 APP = ammonium polyphosphate                                             
 DOT = disodium octaborate tetrahydrite                                   
 C = comparative                                                          
EXAMPLES 15 and 16 (comparative)
The procedure of Example 1 is again followed except that the overlay and decor paper are eliminated. When (15) boric acid is used at 12% the Oxygen Index is 53, the Arapahoe Smoke is 1.3 and the ASTM E-84 Smoke & Flame Spread are 0/0 and 15/15, respectively.
Replacement of the boric acid with 15% of (16) DOT results in the following: Oxygen Index 42, Aropahoe Smoke 1.6 and ASTM E-84 Smoke & Flame Spread 0/0 and 15/15, respectively. Example 16C, when considered with Example 10C above shows the inconsistency of DOT as a flame-retardant herein. See also Table V, below.
EXAMPLES 17-35
Using various concentrations of boric acid, either linerboard or corrugated kraft fiber and various thermosetting phenolic resins in the procedure of Example 1, the results set forth in Table II, below, are achieved. Plate Scumming refers to the damage done to the press plate during heat and pressure consolidation due to an interaction between the resin and the flame-retardant additive.
                                  TABLE II                                
__________________________________________________________________________
           Resin In Core         Arapahoe                                 
                                       Plate                              
Example                                                                   
     Fiber Type %  % Boric Acid                                           
                          Oxygen Index                                    
                                 Smoke Scumming                           
__________________________________________________________________________
17C  Linerboard                                                           
           A    20 4.0    38     1.59  No                                 
18C  "     A    27 3.1    38     1.50  No                                 
19   "     A    18 7.3    48     1.60  No                                 
20   "     A    27 6.2    44     1.62  No                                 
21   "     A    21 17.1   61     1.58  No                                 
22   "     A    28 12.9   56     1.77  No                                 
23   "     A    19 22.4   75     1.39  No                                 
24   "     A    25 17.2   73     1.33  No                                 
25   "     A    25 5.9    44     2.15  No                                 
26   "     A    29 6.8    43     1.65  No                                 
27   "     A    30 6.9    42     1.35  No                                 
28   "     A    29 5.3    42     1.85  No                                 
29   "     A    29 6.7    44     1.65  No                                 
30   "     A    29 8.0    46     1.96  No                                 
31   "     A    29 6.8    44     1.75  No                                 
32C  Corrugated                                                           
           A    29 3.4    38     2.22  No                                 
33   "     A    28 6.4    46     1.78  No                                 
34   "     A    27 9.4    56     1.66  No                                 
35   Linerboard                                                           
           B    28 6.5    43     1.39  No                                 
__________________________________________________________________________
 A = twostep phenolic resin                                               
 B = onestep phenolic resin                                               
EXAMPLES 36-38
Following the procedure of Example 1 except that ammonium pentaborate is substituted for the boric acid therein, the following results, set forth in Table III, are attained:
              TABLE III                                                   
______________________________________                                    
Ex-  Resin                       Arap-                                    
am-  In Core  Ammonium    Oxygen ahoe  Plate                              
ple  Type   %     Pentaborate %                                           
                            Index  Smoke Scumming                         
______________________________________                                    
36C  A      30    3.4       39     1.64  No                               
37   A      30    3.9       43     1.73  No                               
38   B      27    6.3       45     1.64  No                               
______________________________________                                    
 Type A = twostep phenolic resin                                          
 Type B = onestep phenolic resin                                          
EXAMPLES 39-60 (Comparative)
Following the procedure of Example 1 various additional commercially available flame-retardant materials are used as replacements for the boric acid thereof using linerboard kraft fiber and various resins. The results are set forth in Table IV, below.
                                  TABLE IV                                
__________________________________________________________________________
Resin In Core                                                             
Example                                                                   
     Type                                                                 
         %   Flame-Retardant %                                            
                          Oxygen Index                                    
                                 Arapahoe Smoke                           
                                          Plate Scumming                  
__________________________________________________________________________
39C  A   31  STP      7.1 39     1.09     Yes                             
40C  B   24  STP      5.6 38     1.34     Yes                             
41C  A   28  SB       3.2 38     1.82     No                              
42C  A   27  SB       6.3 41     0.75     No                              
43C  B   27  SB       6.2 41     1.50     No                              
44C  A   30  DOT      3.4 39     1.54     No                              
45C  A   30  DOT      6.9 43     1.62     No                              
46C  B   29  DOT      6.7 42     1.55     No                              
47C  A   30  STP/BA   3.5/3.5                                             
                          41     1.56     Yes                             
48C  A   30  ZB       3.4 36     1.25     --                              
49C  A   28  ZB       6.4 37     1.68     --                              
50C  A   29  ZB/APP   1.3/6.7                                             
                          47     2.26     --                              
51C  A   29  ZB/APP   6.7/1.3                                             
                          40     2.37     --                              
52C  A   .sup. 28*                                                        
             ADHP/BA  3.2/3.2                                             
                          40     1.22     Yes                             
53C  A   .sup. 28*                                                        
             ADHP/OA  6.4/1.3                                             
                          48     2.15     Yes                             
54C  A   .sup. 28*                                                        
             ADHP/STP 3.2/3.2                                             
                          40     2.55     Yes                             
55C  A   .sup. 28*                                                        
             ADHP/STP/BA                                                  
                      3.2/2/2                                             
                          41     1.68     Yes                             
56C  A   .sup. 28*                                                        
             ADHP/CaCl.sub.3                                              
                      6.4/2.0                                             
                          45     2.37     Yes                             
57C  A   27  TCP      2.7 36     2.59     --                              
58C  A   27  TCP/APP  0.3/5.8                                             
                          38     3.06     --                              
59C  A   26  TCP/APP  0.6/5.4                                             
                          43     2.74     --                              
60C  A   28  TCP/APP  1.3/5.1                                             
                          43     2.92     --                              
__________________________________________________________________________
 *estimated                                                               
 STP = sodium tetraborate pentahydrate                                    
 SB = sodium borate product                                               
 OA = oxalic acid                                                         
 ADHP = ammonium dihydrogen phosphate                                     
 BA = boric acid                                                          
 ZB = zinc borate                                                         
 TCP = trischloroethyl phosphonate                                        
 DOT = disodium octaborate tetrahydrite                                   
EXAMPLES 62-70 (Comparative)
When disodium octaborate tetrahydrite (DOT) is used to replace boric acid, following the procedure of Example 1 and at higher concentrations than shown in Table IV, the results shown in Table V, are achieved.
              TABLE V                                                     
______________________________________                                    
Example       DOT %    Oxygen Index                                       
______________________________________                                    
62C           20       43                                                 
63C           20       44                                                 
64C           25       48                                                 
65C           30       54                                                 
66C           30       49                                                 
67C           10.5     44                                                 
68C           12       46                                                 
69C           8        41                                                 
70C           8        44                                                 
______________________________________                                    
This table again shows the inconsistency of DOT as a flame-retardant.
EXAMPLE 71C
When ammonium dihydrogen phosphate is substituted for the boric acid of Example 1, the Arapahoe Smoke is substantially always greater than 1.9.
EXAMPLES 72-74C
When aluminum trihydrate is employed in lieu of the boric acid of Example 1 at concentrations of (72C) 5%, (73C) 10% and (74C) 15%, the Oxygen Index values recorded are 34, 34 and 36, respectively.
EXAMPLES 75-77C
Replacement of the boric acid Example 1 by mixtures of antimony oxide with 5% DOT at concentrations of (75C) 1.25%, (76C) 2.5% and (77C) 5.0%, result in Oxygen Index values of 39.5, 40 and 42.5, respectively.

Claims (12)

We claim:
1. A fire-retardant heat and pressure consolidated article comprising,
(a) a monostichous layer of randomly oriented, substantially non-hydrogen bonded, cellulosic fibers from about 0.5 mm to 2.5 mm in average length, said layer being from about 0.25 mm to 2.25 mm thick and containing from about 20% to 35%, by weight, based on the total weight of fiber, resin and flame retardant in (a), of a thermoset resin and a flame-retarding amount (a) of boric acid or ammonium pentaborate.
2. An article in accordance with claim 1 containing, positioned atop said (a), (b) a thermost resin impregnated, decorative sheet.
3. An article in accordance with claim 2 containing, positioned atop said (b), (c) a thermoset resin impregnated alpha-cellulose transparent overlay sheet.
4. An article in accordance with claim 3 wherein the thermoset resin in (a) is a phenolic resin and the thermoset resin in (b) and (c) is a melamine/formaldehyde resin.
5. An article in accordance with claim 2 wherein the thermoset resin in (a) is a phenolic resin and the thermoset resin in (b) is a melamine/formaldehyde resin.
6. An article in accordance with claim 1 in which the flame-retardant is boric acid.
7. An article in accordance with claim 1 wherein the thermoset resin in (a) is a phenolic resin.
8. A method of producing the article of claim 1 which comprises,
(1) defibrating cellulosic fibers to produce fibers of an average length of about 0.5 to 2.5 mm in the presence of air to thereby form an air-fiber stream,
(2) incorporating into said air-fiber stream from about 20% to about 35%, by weight, based on the total weight of fiber and resin, of particles of a thermosetting resin and a flame-retarding amount of boric acid or ammonium pentaborate to thereby form an air-fiber-resin flame-retardant stream,
(3) depositing the fibers, flame-retardant and resin from said air-fiber-resin flame-retardant stream onto a foraminous belt at a thickness ranging from about 5 to about 100 mm,
(4) pre-consolidating the deposited fibers, flame retardant and resin to a thickness of from about 0.5-10.0 mm to form a pre-consolidated layer,
(5) heat and pressure consolidating said pre-consolidated layer.
9. A method in accordance with claim 8 wherein said pre-consolidated layer is formed into a laminate assembly comprising, in superimposed relationship, (A) said pre-consolidated layer and (B) a thermosetting resin impregnated decorative sheet before conducting said step (5).
10. A method in accordance with claim 9 wherein said laminate assembly contains, atop said (B), (C) a thermosetting resin impregnated, alpha-cellulose overlay sheet.
11. A method in accordance with claim 8 wherein said thermosetting resin in said air-fiber-flame-retardant resin stream is a phenolic resin.
12. A method according to claim 8 wherein the flame-retardant is boric acid.
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* Cited by examiner, † Cited by third party
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US4457978A (en) * 1983-05-16 1984-07-03 Stanley Wawzonek Formaldehyde depressed particle board
US4597930A (en) * 1983-07-11 1986-07-01 Szal John R Method of manufacture of a felted fibrous product from a nonaqueous medium
US4647324A (en) * 1985-05-24 1987-03-03 United Technologies Automotive Trim, Inc. Process for pre-resinating cellulose fibers for cellulose composite structures
EP0379100A1 (en) * 1989-01-17 1990-07-25 Hoechst Aktiengesellschaft Flame-resistant carrier web for bitumen webs, and process for producing the same
WO1990011184A1 (en) * 1989-03-20 1990-10-04 Weyerhaeuser Company Method of treating discontinuous fibers
US5064689A (en) * 1989-03-20 1991-11-12 Weyerhaeuser Company Method of treating discontinuous fibers
US5071675A (en) * 1989-03-20 1991-12-10 Weyerhaeuser Company Method of applying liquid sizing of alkyl ketene dimer in ethanol to cellulose fibers entrained in a gas stream
US5230959A (en) * 1989-03-20 1993-07-27 Weyerhaeuser Company Coated fiber product with adhered super absorbent particles
US5300192A (en) * 1992-08-17 1994-04-05 Weyerhaeuser Company Wet laid fiber sheet manufacturing with reactivatable binders for binding particles to fibers
US5308896A (en) * 1992-08-17 1994-05-03 Weyerhaeuser Company Particle binders for high bulk fibers
EP0599812A2 (en) * 1989-06-07 1994-06-01 Chisso Corporation Cellulose-based, inflammable, bulky processed sheets and method for making such sheets
US5352480A (en) * 1992-08-17 1994-10-04 Weyerhaeuser Company Method for binding particles to fibers using reactivatable binders
US5432000A (en) * 1989-03-20 1995-07-11 Weyerhaeuser Company Binder coated discontinuous fibers with adhered particulate materials
US5482666A (en) * 1993-09-15 1996-01-09 Sunds Defibrator Industries Aktiebolag Manufacture of fiberboard by independently controlling temperature and moisture content
US5498478A (en) * 1989-03-20 1996-03-12 Weyerhaeuser Company Polyethylene glycol as a binder material for fibers
US5538783A (en) * 1992-08-17 1996-07-23 Hansen; Michael R. Non-polymeric organic binders for binding particles to fibers
US5543215A (en) * 1992-08-17 1996-08-06 Weyerhaeuser Company Polymeric binders for binding particles to fibers
US5547541A (en) * 1992-08-17 1996-08-20 Weyerhaeuser Company Method for densifying fibers using a densifying agent
US5547745A (en) * 1992-08-17 1996-08-20 Weyerhaeuser Company Particle binders
US5582644A (en) * 1991-12-17 1996-12-10 Weyerhaeuser Company Hopper blender system and method for coating fibers
US5589256A (en) * 1992-08-17 1996-12-31 Weyerhaeuser Company Particle binders that enhance fiber densification
US5641561A (en) * 1992-08-17 1997-06-24 Weyerhaeuser Company Particle binding to fibers
US5723020A (en) * 1995-09-14 1998-03-03 Westvaco Corporation Fire-retardant saturating kraft paper
US5807364A (en) * 1992-08-17 1998-09-15 Weyerhaeuser Company Binder treated fibrous webs and products
US5998032A (en) * 1992-08-17 1999-12-07 Weyerhaeuser Company Method and compositions for enhancing blood absorbence by superabsorbent materials
US6340411B1 (en) 1992-08-17 2002-01-22 Weyerhaeuser Company Fibrous product containing densifying agent
US6391453B1 (en) * 1992-08-17 2002-05-21 Weyernaeuser Company Binder treated particles
US7144474B1 (en) 1992-08-17 2006-12-05 Weyerhaeuser Co. Method of binding particles to binder treated fibers
US20130274382A1 (en) * 2010-12-30 2013-10-17 Chaofeng Xiao Plate synthesized by waste circuit board powder and manufacturing process thereof

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Cited By (51)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4457978A (en) * 1983-05-16 1984-07-03 Stanley Wawzonek Formaldehyde depressed particle board
US4597930A (en) * 1983-07-11 1986-07-01 Szal John R Method of manufacture of a felted fibrous product from a nonaqueous medium
US4647324A (en) * 1985-05-24 1987-03-03 United Technologies Automotive Trim, Inc. Process for pre-resinating cellulose fibers for cellulose composite structures
EP0379100A1 (en) * 1989-01-17 1990-07-25 Hoechst Aktiengesellschaft Flame-resistant carrier web for bitumen webs, and process for producing the same
WO1990011184A1 (en) * 1989-03-20 1990-10-04 Weyerhaeuser Company Method of treating discontinuous fibers
US5057166A (en) * 1989-03-20 1991-10-15 Weyerhaeuser Corporation Method of treating discontinuous fibers
US5064689A (en) * 1989-03-20 1991-11-12 Weyerhaeuser Company Method of treating discontinuous fibers
US5071675A (en) * 1989-03-20 1991-12-10 Weyerhaeuser Company Method of applying liquid sizing of alkyl ketene dimer in ethanol to cellulose fibers entrained in a gas stream
US5230959A (en) * 1989-03-20 1993-07-27 Weyerhaeuser Company Coated fiber product with adhered super absorbent particles
US6270893B1 (en) 1989-03-20 2001-08-07 Weyerhaeuser Company Coated fiber product with adhered super absorbent particles
US5498478A (en) * 1989-03-20 1996-03-12 Weyerhaeuser Company Polyethylene glycol as a binder material for fibers
US5432000A (en) * 1989-03-20 1995-07-11 Weyerhaeuser Company Binder coated discontinuous fibers with adhered particulate materials
US5516585A (en) * 1989-03-20 1996-05-14 Weyerhaeuser Company Coated fiber product with adhered super absorbent particles
EP0599812A2 (en) * 1989-06-07 1994-06-01 Chisso Corporation Cellulose-based, inflammable, bulky processed sheets and method for making such sheets
EP0599812A3 (en) * 1989-06-07 1994-12-07 Chisso Corp Cellulose-based, inflammable, bulky processed sheets and method for making such sheets.
US5582644A (en) * 1991-12-17 1996-12-10 Weyerhaeuser Company Hopper blender system and method for coating fibers
US5571618A (en) * 1992-08-17 1996-11-05 Weyerhaeuser Company Reactivatable binders for binding particles to fibers
US6395395B1 (en) 1992-08-17 2002-05-28 Weyerhaeuser Company Method and compositions for enhancing blood absorbence by superabsorbent materials
US5447977A (en) * 1992-08-17 1995-09-05 Weyerhaeuser Company Particle binders for high bulk fibers
US5538783A (en) * 1992-08-17 1996-07-23 Hansen; Michael R. Non-polymeric organic binders for binding particles to fibers
US5543215A (en) * 1992-08-17 1996-08-06 Weyerhaeuser Company Polymeric binders for binding particles to fibers
US5547541A (en) * 1992-08-17 1996-08-20 Weyerhaeuser Company Method for densifying fibers using a densifying agent
US5547745A (en) * 1992-08-17 1996-08-20 Weyerhaeuser Company Particle binders
US5352480A (en) * 1992-08-17 1994-10-04 Weyerhaeuser Company Method for binding particles to fibers using reactivatable binders
US5308896A (en) * 1992-08-17 1994-05-03 Weyerhaeuser Company Particle binders for high bulk fibers
US5589256A (en) * 1992-08-17 1996-12-31 Weyerhaeuser Company Particle binders that enhance fiber densification
US5607759A (en) * 1992-08-17 1997-03-04 Weyerhaeuser Company Particle binding to fibers
US5609727A (en) * 1992-08-17 1997-03-11 Weyerhaeuser Company Fibrous product for binding particles
US5611885A (en) * 1992-08-17 1997-03-18 Weyerhaeuser Company Particle binders
US5614570A (en) * 1992-08-17 1997-03-25 Weyerhaeuser Company Absorbent articles containing binder carrying high bulk fibers
US5641561A (en) * 1992-08-17 1997-06-24 Weyerhaeuser Company Particle binding to fibers
US5672418A (en) * 1992-08-17 1997-09-30 Weyerhaeuser Company Particle binders
US5693411A (en) * 1992-08-17 1997-12-02 Weyerhaeuser Company Binders for binding water soluble particles to fibers
US7144474B1 (en) 1992-08-17 2006-12-05 Weyerhaeuser Co. Method of binding particles to binder treated fibers
US5789326A (en) * 1992-08-17 1998-08-04 Weyerhaeuser Company Particle binders
US5807364A (en) * 1992-08-17 1998-09-15 Weyerhaeuser Company Binder treated fibrous webs and products
US5998032A (en) * 1992-08-17 1999-12-07 Weyerhaeuser Company Method and compositions for enhancing blood absorbence by superabsorbent materials
US6071549A (en) * 1992-08-17 2000-06-06 Weyerhaeuser Company Binder treated fibrous webs and products
US5300192A (en) * 1992-08-17 1994-04-05 Weyerhaeuser Company Wet laid fiber sheet manufacturing with reactivatable binders for binding particles to fibers
US6340411B1 (en) 1992-08-17 2002-01-22 Weyerhaeuser Company Fibrous product containing densifying agent
US6391453B1 (en) * 1992-08-17 2002-05-21 Weyernaeuser Company Binder treated particles
US7018490B2 (en) 1992-08-17 2006-03-28 Weyerhaeuser Company Method of binding binder treated particles to fibers
US6425979B1 (en) 1992-08-17 2002-07-30 Weyerhaeuser Company Method for making superabsorbent containing diapers
US6461553B1 (en) 1992-08-17 2002-10-08 Weyerhaeuser Method of binding binder treated particles to fibers
US6521087B2 (en) 1992-08-17 2003-02-18 Weyerhaeuser Company Method for forming a diaper
US6521339B1 (en) 1992-08-17 2003-02-18 Weyerhaeuser Company Diol treated particles combined with fibers
US6596103B1 (en) 1992-08-17 2003-07-22 Weyerhaeuser Company Method of binding binder treated particles to fibers
US6627249B2 (en) 1992-08-17 2003-09-30 Weyerhaeuser Company Method of enhancing blood absorbence by superabsorbent material
US5482666A (en) * 1993-09-15 1996-01-09 Sunds Defibrator Industries Aktiebolag Manufacture of fiberboard by independently controlling temperature and moisture content
US5723020A (en) * 1995-09-14 1998-03-03 Westvaco Corporation Fire-retardant saturating kraft paper
US20130274382A1 (en) * 2010-12-30 2013-10-17 Chaofeng Xiao Plate synthesized by waste circuit board powder and manufacturing process thereof

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